Risk factors for PICU mortality
Overall PICU mortality for all admissions was 46.2% (24/52). There were no significant difference between survivors and nonsurvivors with respect to age, sex, EBV infection, Pediatric Risk of Mortality III (PRISM III) score at PICU admission, and the type of SHLH. For all patients, the factors that were significantly different between survivors and nonsurvivors were the length of PICU stay, number of organ dysfunction, mechanical ventilation, and vasoactive agents needed.
Table 1 lists data comparing laboratory variables for survivors versus non-survivors. TBIL, DBIL, ALT, AST, ALB, PT, FIB, BUN and CR, as well as WBC, HB, PLT level at CRRT initiation were no different for survivors compared to non-survivors. In contrast, non-survivors had significantly higher levels of serum LDH (1404.5 (713.25, 2793) vs. 982.7 (692, 1461) (U/L), P = 0.037), LAC(1.9 (1.3, 4.53) (mmol/L) vs. 1.65 (0.8, 2.45) , P=0.034 ), triglyceride (2.88 (1.94, 5.08) (mmol/L) vs. 2.41 (1.63, 3.32), P=0.032) at CRRT initiation.
In addition, patients with SHLH and MODS who died during their hospital displayed a significantly higher IL-6 (28.66 (17.77, 113.63) (pg/ml) vs.0.98 (0.1, 4.63) P=0.000) at CRRT initiation when compared to those who survived. No difference was observed in serum IL-1, IL-10, TNF-a, SCD25, IL-8, IL-12 and IL-18 between patients discharged alive from PICU and those who died during PICU stay.
Logistic regression analysis using PICU mortality as the endpoint was performed on categorical and continuous variables. Regression modeling identified two independent risk factors of mortality: the number of Organ dysfunction (OR: 3.464; 95% CI [1.018-11.788], P=0.047), and the serum IL-6 level (OR:1.388; 95% CI [1.058-1.821], P= 0.018). Receiver Operating Characteristic (ROC) curve was used to evaluate the power of the two independent variables. The number of Organ dysfunction and the serum IL-6 level at PICU admission were found high discriminative power with AUC values respectively of 0.896 (SE 0.046, 95% CI 0.806-0.986) and 0.964 (SE 0.026, 95% CI 0.913-1.00) (Table 2).
Furthermore, we used the highest Youden Index to determine the most discriminative cut-off point for the number of Organ dysfunction and the serum IL-6 level at PICU admission to predict PICU mortality (Table 3-4, Figure 1). A value of serum IL-6 level of 13.12pg/ml and the number of Organ dysfunction of 3 at CRRT initiation have been identified as cut-off points.